Immigration is, I believe, a human right. It's liberty - liberty to travel, to make the most of yourself, and it's opportunity. People should be free to make the most of themselves. It's also economic freedom, which generally yields more productive economies for all.
For practical reasons, mostly to prevent the economic shocks of mass migrations, it needs to be somewhat limited and controlled. But I want the poorest, most oppressed people coming to my country; they are the ones who need freedom the most - the most marginal social and economic gain. I'm completely confident that they and their children will thrive and make my country better. And for practical and moral reasons, I'd like more diversity; the sooner we can do away with the dominance of any ethnic group, the sooner we can be rid of their BS bigotry, which is a drain on us all. (Imagine, for a moment, the world without bigots - so many problems solved.)